Process for producing saturated



Oct. 23, 1962 HAJIME MIHARA ETAL 3,060,211

PROCESS FOR PRODUCING SATURATED ALIPHATIC ACIDS Filed D60. l0, 1959 INVENTORS Hailm Mih ara chlro Mlwa Kisaburo Ue no Syugo Morl'ra ATTORNEYS nie States The present invention relates generally to an improved chemical process and it relates more particularly to an improved process for producing saturated aliphatic acids from unsaturated aliphatic compounds and specifically to the production of azelaic acid, pelarponic acid and caproic acid from rise bran fatty acid, tall oil fatty acid and to the production of azelaic acid and pelargonic acid from commercial grade oleic acid.

The reaction between ozone and the ethylenic bond of an unsaturated fatty acid such as oleic acid to produce thereby carboxyl and carbonyl radicals is well known. It has been employed in the production of saturated aliphatic acids from unsaturated fatty acids. However, the processes herebefore employed possessed numerous drawbacks and disadvantages. The yield of the desirable taturated aliphatic acida was low and the process relatively complex, leaving much to be desired.

lt is therefore a principal object of the present invention to provide an improved method of producing saturated aliphatic acids from unsaturated fatty acids.

Another object of the present invent-ion is to provide an improved process for the production of azelaic acid, pelargonic acid and caproic acid from rice bran oil fatty acid, tall oil fatty acid and for the production of azelaic acid and pelargonic acid from commercial grade oleic acid.

Still another object of the present invention is to provide a process of the above nature characterized by a relatively high yield.

The above and further objects of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawing which illustrates an apparatus with which the present improved process may be practiced.

It has been found that in the production of saturated aliphatic acids such as azelaic acid, pelargonic acid and caproic acid from unsaturated fatty acid materials such as rice bran oil fatty acid, tall oil fatty acid and commercial grade oleic acid, by the process of treating the unsaturated fatty acid with ozone and decomposing and oxidizing the resulting ozonide a rad-ical increase in the yield is achieved by conducting the pro-cess and particularly the decomposition step in the presence of a reaction promoting agent. The reaction promoting agents which may be advantageously employed are the phosphoric acids such as orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, phosphorous acid, polyphosphoric acids and phosphoric anhydride and derivatives thereof such as the organic esters trioctyl phosphate, tributyl phosphate, triethyl phosphate, ethylmetaphosphate, butyl pyrophosphate, tricresyl phosphate and octyl phosphite. The reaction promoting agent may be individually employed or a mixture of two or more may be employed and may be added to the unsaturated fatty acid prior to ozonization thereof or to the ozonide prior to decomposition thereof. The amount of promoting agent should be between 0.01% and by weight of the unsaturated fatty acids.

Thus the present invention in a sense contemplates the improved process of producing saturated aliphatic acids from unsaturated fatty acids in which the fatty acid is ozonized a-nd the ozonide decomposed and oxidized, the

atent nricc step of effecting such process in the presence of a reaction promoting agent.

Referring now to the drawing which illustrates an apparatus by which ozonization of the fatty acid may be effected the reference numeral 1 generally designates a tank of oxygen under pressure which is connected by way of a valve 2 and piping 3 to a gas dryer 4. A conventional flowmeter 6 and a 4manometer 7 communicate with the pipe 3 to measure the oxygen ilow and pressure. From the dryer 4 the oxygen flows through an ozonizer 8 and by way of a blow pipe 9 to the bottom of an ozone absorbing chamber 10. The ozone absorbing chamber 10 is formed of glass and is 50 mm. in diameter and 300 mm. high and is provided with a thermometer 11 extending to the bottom of the chamber 10. The ozonizer 8 is of the electrical discharge type in which -a brush or corona discharge is established in the ozonizing zone by means of a high voltage derived from the secondary of a step-up transformer 12 the primary of which is connected to a source of alternating current. The oxygenpasses through the ozonizing zone and leaves it with an ozone concentration which may be readily adjusted. The gas leaving the absorbing chamber 10 passes out by way of a tubular leg in the upper section of the chamber 10 and flows through a condenser 13 to exhaust. The gas entering and leaving the absorbing chamber 10 may be analyzed by sampling from the valved outlets 16 and 17 respectively to determine the ozone content thereof.

The following examples are given merely by way of illustration of the present process, the apparatus above described being employed therein. The Ifatty acid materials being treated in these examples having the following compositions.

(a) Analysis of rice bran oil fatty acid:

Percent Oleic acid 40.2 Linoleic acid 29.8 Palmitic acid 17.5 Undecomposed oil 4.2 Wax 7.2 Moisture and others 1.1

(b) Tall oil fatty acid:

Oleic acid 52.9 Linoleic acid 44.1 Saturated fatty acid 1.0 Rosin acid 1.0 Unsaponiflable matters 1.0

Example 1 50 grams of rice bran oil fatty acid, 1250 grams of glacial acetic acid and 0.5 gram of orthophosphoric acid of 89% purity are placed in `the chamber 10 and maintained at a temperature of 20 C. A 2% ozone concentration oxygen is fed into the bottom of the chamber 10 at the rate of 2 liters per minute until no more ozone is absorbed as evidenced by the ozone content of the outlet gas. The amount of ozone required was 1.3 times the quantity calculated from the iodine number of the treated material. The reacted materials are heated to C. for one hour to completely decompose the resulting ozonides after which 0.01 gram of manganese acetate, an oxidation catalyst, is -added and oxygen fed therethrough at the rate of l -liter per minute for three hours while maintaining the tempera-ture at 100 C. to completely oxidize the decomposition products, mainly aldehydes.

The resulting oxidized product is then distilled at normal pressure to remove the solvent, acetic acid, and is then subjected to vacuum distillation. There Were produced 5.0 grams of caproic acid having a boiling point of to 110 C. at 15 mm. Hg and a neutralization number of 487 and 8.9 grams of pelargonic acid having a boiling point of 142 to 147 C. at 15 mm. Hg and a neutralization number of 353, leaving a distillation residue of 40 grams having a neutralization number of 385. The distillation residue is extracted four times with ve times its Weight of hot water and the extract treated with activated carbon in the hot state and filtered. The filtrate is concentrated by evaporation and upon cooling produced 19.1 grams of crystal azelaic acid in the form of white flakes having a neutralization number of 595 and a melting point of 104 to 105 C.

By contrast, when the above procedure and conditions were closely followed with the exception that the promoting agent, orthophosphoric acid was emitted, there were produced from 50 grams of rice bran oil fatty acid, 4.3 grams of caproic acid having a boiling point of 105 to 110 C., at l5 mm. Hg and a neutralization number of 487, 7.7 grams of pelargonic acid having a boiling point of 142 to 147 C. at 15 mm. Hg and a neutralization number of 353 and 45 grams of distillation residue with a. neutralization number of 355 from which no more than 16.1 grams of azelaic acid were obtained. It is obvious from the above that the use of the promoting agent in the present process greatly increases the yield of the saturated aliphatic acids.

Example 2 50 grams of tall oil fatty acid, 250 grams of glacial acetic acid and 0.05 gram of tricresyl phosphate are placed in the chamber and while maintained at a temperature of C. a 1% ozone concentration oxygen is fed therethrough at the rate of 2 liters per minute until no additional ozone is absorbed. The amount of ozone thus required was 1.3 times the quantity calculated from the iodine number of the treated material. There is then added 0.01 gram of manganese acetate to the ozonized material and the temperature thereof raised to 100 C. while oxygen is fed therethrough at the rate of 1 liter per minute for three hours to completely simultaneously effect the decomposition of the ozonide andl the oxidation of the decomposed product.

After removing the solvent, acetic acid, from the oxidation product by distillation under normal pressure, the oxidation product is subjected to vacuum distillation. There were obtained 7.3 grams of caproic acid with a boiling point of 105 to 110 C. at 15 mm. Hg and a neutralization number of 480 and 12.1 grams of pelargonic acid with a boiling point of 142 to 147 C. at 15 mm. Hg and a neutralization number of 355 leaving a residue of 40 grams with a neutralization number of 382. The distillation residue is extracted four times with tive times its weight of hot water and the extract treated in the hot state with activated carbon and ltered. The ltrate is concentrated by evaporation and cooled to produce 25.6 grams of crystal azelaic acid in the form of white flakes having a neutralization number of 593 and a melting point of 104 to 106 C.

Where the last procedure and conditions were closely followed in processing 50 grams of tall oil fatty acid except that the promoting agent tricresyl phosphate was omitted, there were produced 5.5 grams of caproic acid with a boiling point of 105 to 110 C. at 15 mm. Hg and a neutralization number of 490 and 8.9 grams of pelargonic acid with a boiling point of 142 to 147 C. at 15 mm. Hg and a neutralization number of 350 leaving a distillation residue of 44 grams with a neutralization number of 340. No more than 19.5 grams of azelaic acid having a melting point of 104r to 105 C. and a neutralization number of 590 were obtained from the residue. Here again it is apparent that the use of the reaction promoting agent radically increases the yield of the saturated aliphatic acids.

A study was made in order to determine at which stage in the process the reactionV promoting agent acts or is effective. To this end the process Was conducted with the reaction promoting agent added alternatively following the ozonization and decomposition steps. More particularly 50 grams of rice bran fatty acid and 250 grams of glacial acetic acid were placed in the chamber 10. Oxygen having a 2% ozone concentration was fed therethrough at the rate of two liters per minute while maintaining a temperature of 20 C. until no further ozone was absorbed. The amount of ozone required was 1.3 times the amount calculated from the iodine value of the fatty acid.

Following the ozonization, 0.5 gram of orthophosphoric acid of 89% purity was added and the material heated for one hour at C. to completely decompose the ozonide. 0.01 gram of manganese acetate was added to the decomposed product and oxygen fed therethrough at the rate of 1 liter per minute for three hours to completely oxidize the aldehydes. The oxidized product was then treated as in Examples 1 and 2 to produce 5 grams of caproic acid with a boiling point of to 110 C. at 15 mm. Hg and a neutralization number of 485 and 9.0 grams of pelargonic acid with a boiling point of 142 to 147 C. at 15 mm. Hg and a neutralization number of 386 leaving a distillation residue of 40 grams with a neutralization number of 350. The residue is extracted and the extract puried and cooled as aforesaid to produce 18.9 grams of crystal azelaic acid in the form of a white flake with a melting point of 104 to 106 C. and a neutralization number of 593. The relatively high yield indicates that the reaction promoting agent is effective in the decomposition or oxidation stage but not in the ozonization step.

To determine in which of the latter stages the reaction promoting agent was effective 5 0 grams of rice bran fatty acid and 250 grams of glacial acetic acid were added to the chamber 10 and maintained at 20 C. While 2% ozone concentration oxygen was fed therethrough at the rate of 2 liters per minute until no further ozone was absorbed, fat which time 1.3 times the quantity calculated from the fattty acid iodine number was consumed. The ozonized material was heated for one 'hour at 100 C. to decompose the Ozonide. To the 4decomposed material were added 0.01 gram of manganese acetate :and 0.5 gram of 89% pure orthophosphoric acid and oxygen was fed therethrough as :aforesaid at the rate of 1 liter per minute for three hours to completely oxidize the aldehydes. The oxidized product was then treated las in the earlier examples to produce 4.0 grams of caproic acid with a boiling point of 105 to 110 C. at l5 mm. Hg and a neutralization number of 483 and 7.5 grams of pelargonic acid with a neutralization number of 350 leaving a 43 gram distillation residue with a neutralization number of 345. The residue was extracted as aforesaid to produce 16.0 grams of crystal azelaic acid in the form of White flakes with va melting point of 103 to 104 C. and a neutralization number of 590. Thus, the reaction promoting agent evidenced no effect in the oxidation step.

It may be concluded from the above that in the present process of producing saturated aliphatic acids from unsaturated f-atty acids, the activity of the promoting `agent is in the decomposition of the ozonides. Although there have 'been many explanations offered the mechanism of ozone oxidation reactions of the present type remains in doubt. How the reaction promoting agent acts is unknown ybut it is believed that it inhibits polymerization during the decomposition of the ozonides. This is supported by the increased yields of the desired monobasic and dibasic acids land the formation of little polymer.

As many different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to `be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

What is claimed is:

1. In the process of producing la saturated aliphatic acid from an unsaturated fatty 4acid comprising ozonizing an unsaturated fatty acid to forman ozonide thereof, decomposing said ozonide and oxidizing the resulting decomposition product to produce said aliphatic acid, the improvement which comprises effecting said process 111 the presence of a reaction promoting agent selected from the group consisting of phosphoric acids `and their esters, whereby the yield of said aliphatic acid is increased.

2. The process of producing a saturated aliphatic acid from an unsaturated fatty acid comprising ozonizing said unsaturated fatty acid to form an ozonide thereof, decomposing said ozonide in the presence 4of a `reaction promoting agent selected from the class consisting of the inorganic phosphoric lacids and their hydrocarbon esters and oxidizing the resulting decomposed product to produce said satin-ated aliphatic acid.

3. The process of producing a saturated aliphatic acid from au unsaturated fatty acid comprising passing an ozone containing gas through said fatty acid to form the ozonide thereof, decomposing said `ozonide in the presence of a reaction promoting agent selected from the class consisting of the inorganic phosphoric acids and their hydrocarbon esters `and oxidizing the resulting decomposed products to produce said saturated aliphatic acid.

4. The process in accordance with claim 3 wherein said reaction promoting agent is employed in an amount between 0.01% and Iby weight of said unsaturated fatty acid.

5. The process in laccordance with claim 3 wherein the decomposition step is effected by the heating of said ozonide.

6. The process of claim 2, wherein the react-ion promoting agent is orthophosphoric acid.

7. The process of claim 2, wherein the reaction promoting agent is pyrophosphoric acid.

8. The process of claim 2, wherein the reaction promoting agent is metaphosphoric acid.

9. The process of claim 2, wherein the reaction promoting agent is phosphorous acid.

10. The process of claim 2, wherein the reaction promoting agent is poly-phosphoric acids.

11. The process of claim 2, wherein the reaction promoting agent is phosphoric anhydride. i Y

12. The process of claim 2, wherein the reaction promoting agent is tricresyl phosphate.

13. The process of claim 2, wherein the reaction promoting agent is trioctyl phosphate.

14. The process of claim 2, wherein the reaction promoting agent is tributyl phosphate.

15. The process of claim 2, wherein the reaction promoting agent is triethyl phosphate.

16. The process of claim 2, wherein the reaction promoting agent is ethylmetaphosphate.

17. The process of claim 2, wherein the reaction promoting vagent is butyl pyro-phosphate.

18. The process of claim 2, wherein the reaction promoting agent is octyl phosphite.

19. The process as claimed in claim 3 wherein said unsaturated fatty acid is selected from the class consisting of rice `bran oil fatty acid to produce caproic acid, pelargonic acid and -azelaic acid; tall oil fatty acid to produce caproic acid, pelargonic acid and azelaic acid; and oleic acid to produce azelaic acid and pelargonic acid.

20. The process of producing a saturated aliphatic acid from an unsaturated fatty 'acid comprising ozonizing said unsaturated fatty -acid to form an ozonide thereof, decomposing said ozonide in the presence of catalytic amounts of an hydrocanbon ester of an inorganic phosphoric acid to form a decomposed product, yand oxidizing said decomposed product to produce said saturated aliphatic acid.

21. The process of producing a saturated aliphatic acid from an `unsaturated fatty acid comprising ozonizing said unsaturated fatty acid to `form an ozonide thereof, decomposing said ozonide in the presence of catalytic amounts of an inorganic phosphoric acid to Iform a decomposed product, Iand oxidizing said decomposed prod uct to produce said saturated aliphatic acid.

References Cited in the le of this patent UNITED STATES PATENTS 

1. IN THE PROCESS OF PRODUCING A SATURATED ALIPHATIC ACID FROM AN UNSATURATED FATTY ACID COMPRISING OZONIZING AN UNSATURATED FATTY ACID TO FORM AN OZONIDE THEREOF, DECOMPOSING SAID OZONIDE AND OXIDIZING THE RESULTING DECOMPOSITION PRODUCT TO PRODUCE SAID ALIPHATIC ACID, THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID PROCESS IN THE PRESENCE OF A REACTION PROMOTING AGENT SELECTED FROM THE GROUP CONSISTING OF PHOSPHORIC ACIDS AND THEIR ESTERS WHEREBY THE YIELD OF SAID ALIPHATIC ACID IS INCREASED. 